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32 .Nd protocol for transmitting kernel dumps to a remote server
34 To compile netdump client support into the kernel, place the following line in
35 your kernel configuration file:
36 .Bd -ragged -offset indent
40 netdump is a UDP-based protocol for transmitting kernel dumps to a remote host.
41 A netdump client is a panicking kernel, and a netdump server is a host
44 daemon, available in ports as
45 .Pa ports/ftp/netdumpd .
47 clients are configured using the
52 client messages consist of a fixed-size header followed by a variable-sized
54 The header contains the message type, a sequence number, the offset of
55 the payload data in the kernel dump, and the length of the payload data
56 (not including the header).
58 .Dv HERALD , FINISHED , KDH , VMCORE ,
62 server messages have a fixed size and contain only the sequence number of
64 These messages indicate that the server has successfully processed the
65 client message with the corresponding sequence number.
66 All client messages are acknowledged this way.
67 Server messages are always sent to port 20024 of the client.
73 message to the server at port 20023.
74 The client may include a relative path in its payload, in which case the
76 server should attempt to save the dump at that path relative to its configured
78 The server will acknowledge the
80 using a random source port, and the client must send all subsequent messages
87 message payloads contain the kernel dump header, dump contents, and
88 dump encryption key respectively.
89 The offset in the message header should be treated as a seek offset
90 in the corresponding file.
91 There are no ordering requirements for these messages.
95 is completed by sending the
97 message to the server.
99 The following network drivers support netdump:
113 The following variables are available as both
118 .Bl -tag -width "indent"
119 .It Va net.netdump.debug
120 Control debug message verbosity.
121 Debug messages are disabled by default, but are useful when troubleshooting
122 or when developing driver support.
123 .It Va net.netdump.path
124 Specify a path relative to the server's dump directory in which to store
128 server is configured to store dumps in
132 will cause the server to attempt to store dumps from the client in
134 The server will not automatically create the relative directory.
135 .It Va net.netdump.polls
136 The client will poll the configured network interface while waiting for
138 This parameter controls the maximum number of poll attempts before giving
139 up, which typically results in a re-transmit.
140 Each poll attempt takes 0.5ms.
141 .It Va net.netdump.retries
142 The number of times the client will re-transmit a packet before aborting
143 a dump due to a lack of acknowledgement.
144 The default may be too small in environments with lots of packet loss.
145 .It Va net.netdump.arp_retries
146 The number of times the client will attempt to learn the MAC address of
147 the configured gateway or server before giving up and aborting the dump.
155 client support first appeared in
158 Only IPv4 is supported.
161 may only be used after the kernel has panicked.